Introduction to Dictionary
suggest changeA dictionary is an example of a key value store also known as Mapping in Python. It allows you to store and retrieve elements by referencing a key. As dictionaries are referenced by key, they have very fast lookups. As they are primarily used for referencing items by key, they are not sorted.
creating a dict
Dictionaries can be initiated in many ways:
literal syntax
d = {} # empty dict
d = {'key': 'value'} # dict with initial values
# Also unpacking one or multiple dictionaries with the literal syntax is possible
# makes a shallow copy of otherdict
d = {**otherdict}
# also updates the shallow copy with the contents of the yetanotherdict.
d = {**otherdict, **yetanotherdict}
dict comprehension
d = {k:v for k,v in [('key', 'value',)]}
see also: Comprehensions
built-in class: dict()
d = dict() # emtpy dict
d = dict(key='value') # explicit keyword arguments
d = dict([('key', 'value')]) # passing in a list of key/value pairs
# make a shallow copy of another dict (only possible if keys are only strings!)
d = dict(**otherdict)
modifying a dict
To add items to a dictionary, simply create a new key with a value:
d['newkey'] = 42
It also possible to add list
and dictionary
as value:
d['new_list'] = [1, 2, 3]
d['new_dict'] = {'nested_dict': 1}
To delete an item, delete the key from the dictionary:
del d['newkey']
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